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From: ajayshah@aludra.usc.edu (Ajay Shah)
Newsgroups: comp.lang.pascal
Subject: Re: I/O with complex datastructures
Keywords: I/O datastructures save
Message-ID: <11274@chaph.usc.edu>
Date: 6 Aug 90 20:45:39 GMT
References: <140232@sun.Eng.Sun.COM>
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In article <140232@sun.Eng.Sun.COM> jasonf@cetemp.Eng.Sun.COM (Jason Freund) writes:
>
>	I've never dealt with file I/O in Pascal and I have a question
>about saving a complex datastructure.  Basically, I have a single, very
>complex datastructure that holds just about all of the information in my
>program.  I want to save all of its data into a file so that I can load
>it back up when the program's user wants to change some info in the database.

---------------------------------------------------------------------------
type
	anytype = blahblahblah

procedure savetodisk(fn:fnstring; var r:anytype);  {var for speed}
var f: file of anytype;
begin
	assign(f, fn); rewrite(f); write(f, r); close(f)
end;
---------------------------------------------------------------------------

Strengths: speed; it's very, very fast.

Caveat: you have to thread through complex pointer-oriented
	data-structures "by hand" and then you could easily hit trouble
	since TPascal isn't good at handling files containing hetrogenous
	objects.  Amazingly, the best solution in that case is TP 5.5's
	object-oriented implementation of a stream concept.  It's very
	beautifully done, and is a pleasure to use.

Minor point: you could lookup sizeof(r) to know how big the file
	is going to be.


-- 
_______________________________________________________________________________
Ajay Shah, (213)747-9991, ajayshah@usc.edu
                              The more things change, the more they stay insane.
_______________________________________________________________________________